kunit: tool: misc fixes (unused vars, imports, leaked files)

Drop some variables in unit tests that were unused and/or add assertions
based on them.

For ExitStack, it was imported, but the `es` variable wasn't used so it
didn't do anything, and we were leaking the file objects.
Refactor it to just use nested `with` statements to properly close them.

And drop the direct use of .close() on file objects in the kunit tool
unit test, as these can be leaked if test assertions fail.
Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/kunit/kunit.py

@@ -18,7 +18,6 @@ from collections import namedtuple
 from enum import Enum, auto
 from typing import Iterable, Sequence
 
-import kunit_config
 import kunit_json
 import kunit_kernel
 import kunit_parser

tools/testing/kunit/kunit_kernel.py

@@ -14,10 +14,6 @@ import shutil
 import signal
 from typing import Iterator, Optional, Tuple
 
-from contextlib import ExitStack
-
-from collections import namedtuple
-
 import kunit_config
 import kunit_parser
 import qemu_config
@@ -168,10 +164,10 @@ class LinuxSourceTreeOperationsUml(LinuxSourceTreeOperations):
 		process.wait()
 		kunit_parser.print_with_timestamp(
 			'Disabling broken configs to run KUnit tests...')
-		with ExitStack() as es:
-			config = open(get_kconfig_path(build_dir), 'a')
-			disable = open(BROKEN_ALLCONFIG_PATH, 'r').read()
-			config.write(disable)
+
+		with open(get_kconfig_path(build_dir), 'a') as config:
+			with open(BROKEN_ALLCONFIG_PATH, 'r') as disable:
+				config.write(disable.read())
 		kunit_parser.print_with_timestamp(
 			'Starting Kernel with all configs takes a few minutes...')
 

tools/testing/kunit/kunit_tool_test.py

@@ -185,7 +185,7 @@ class KUnitParserTest(unittest.TestCase):
 				kunit_parser.extract_tap_lines(file.readlines()))
 		print_mock.assert_any_call(StrContains('could not parse test results!'))
 		print_mock.stop()
-		file.close()
+		self.assertEqual(0, len(result.suites))
 
 	def test_crashed_test(self):
 		crashed_log = test_data_path('test_is_test_passed-crash.log')
@@ -197,24 +197,22 @@ class KUnitParserTest(unittest.TestCase):
 
 	def test_skipped_test(self):
 		skipped_log = test_data_path('test_skip_tests.log')
-		file = open(skipped_log)
-		result = kunit_parser.parse_run_tests(file.readlines())
+		with open(skipped_log) as file:
+			result = kunit_parser.parse_run_tests(file.readlines())
 
 		# A skipped test does not fail the whole suite.
 		self.assertEqual(
 			kunit_parser.TestStatus.SUCCESS,
 			result.status)
-		file.close()
 
 	def test_skipped_all_tests(self):
 		skipped_log = test_data_path('test_skip_all_tests.log')
-		file = open(skipped_log)
-		result = kunit_parser.parse_run_tests(file.readlines())
+		with open(skipped_log) as file:
+			result = kunit_parser.parse_run_tests(file.readlines())
 
 		self.assertEqual(
 			kunit_parser.TestStatus.SKIPPED,
 			result.status)
-		file.close()
 
 
 	def test_ignores_prefix_printk_time(self):
@@ -283,13 +281,13 @@ class LinuxSourceTreeTest(unittest.TestCase):
 
 	def test_valid_kunitconfig(self):
 		with tempfile.NamedTemporaryFile('wt') as kunitconfig:
-			tree = kunit_kernel.LinuxSourceTree('', kunitconfig_path=kunitconfig.name)
+			kunit_kernel.LinuxSourceTree('', kunitconfig_path=kunitconfig.name)
 
 	def test_dir_kunitconfig(self):
 		with tempfile.TemporaryDirectory('') as dir:
-			with open(os.path.join(dir, '.kunitconfig'), 'w') as f:
+			with open(os.path.join(dir, '.kunitconfig'), 'w'):
 				pass
-			tree = kunit_kernel.LinuxSourceTree('', kunitconfig_path=dir)
+			kunit_kernel.LinuxSourceTree('', kunitconfig_path=dir)
 
 	# TODO: add more test cases.